Abstract Anthropogenic heat is a strong point source in urban areas, increasing temperature and exacerbating heat‐related health risks. While its impact on urban climate has been widely studied, a simple expression for quickly estimating temperature changes due to anthropogenic heat remains lacking. In this study, we derive such a relation by a novel integration of dimensional analysis with numerical simulations. Our findings show that under mean conditions, anthropogenic heat behaves similarly to a passive scalar, making planetary boundary layer height, wind speed, and urban surface area effective proxies for estimating additional warming. Incorporating radiation, a key factor distinguishing anthropogenic heat from a passive scalar, improves the physical consistency of the relation, particularly at low wind speeds.